When sows have piglets, their offspring must nurse and there is a high mortality rate during the first days of the piglets' life because the sow tends to roll over onto the piglet during feeding or just preparatory to feeding as when the sow tries to lay down. When doing so, there is a substantial risk that it will lay down on a piglet and kill it. Piglet mortality is high.
MCMURRAY et al. in U.S. Pat. No. 3,084,668 issued Apr. 9, 1963 disclosed a farrowing pen construction for positioning the sow in a specially designed farrowing pen to thereby regulate the position to be assumed by the sow, both during normal piglet feeding and during sow eating operations so as to provide a safe movement of the piglets to and fro from the sow.
NOTARIANNI et al. in U.S. Pat. No. 4,159,993 issued Mar. 27, 1979 discloses a piglet saver wherein two adjacent chambers are provided, one for the piglets and one for the sow. The sow is confined so that she may eat standing up or lie down into the suckling position on her side whereupon there is provided an opening between the chambers but only so long as the sow is laying down.
Both of these inventions attempt to reduce the mortality of the piglets.